In manufacturing semiconductor devices, in response to a recent request for high densification and high integration, circuitry tends to have a multi-layered wiring structure. For this reason, a burying technique for an electrical connection of a contact hole which connects an Si substrate as the lower layer and a wiring layer as the upper layer becomes important.
In order to make an ohmic contact between a metal wire (plug) used to bury such a contact hole and an Si substrate as the lower layer, a Ti film is formed on an inner side of the contact hole by a chemical vapor deposition (CVD) method prior to burying the contact hole. Thereafter, a contact area is formed by allowing the base Si substrate to react with the Ti film and selectively growing a TiSix layer on the Si diffusion layer at the bottom of the contact hole, thereby obtaining good ohmic resistance. The described above is a well-known technique.
On the other hand, recently, an Si substrate containing carbon (C) is sometimes used in a logic device and the like. If the above-described technique is applied to the C-containing Si substrate, the Si base substrate becomes difficult to react with Ti, and C is introduced into the contact area, thereby increasing resistance. In addition, along with miniaturization of semiconductor devices, a diffusion layer on a substrate gradually narrows, and accordingly, the formation of the contact layer using the reaction with the substrate is limited.